More than 5,000 ethnic Albanians sought refuge in Kosovo from fighting and ethnic tension in Macedonia on Monday alone taking the total number since Friday to almost 18,000, the UN refugee agency (UNHCR) said here Tuesday.

Some 5,300 people left Macedonia via the main border crossing at Blace on Monday, Kris Janowski, spokesman for the UN High Commissioner for Refugees, told a news briefing.

"Altogether since last Friday we've had nearly 18,000 people fleeing from Macedonia to Kosovo," Janowski told reporters.

Staff at the Blace crossing said several hundred people had already crossed into Kosovo by early Tuesday morning, he added.

They are fleeing a flare-up in fighting between government forces and ethnic Albanian rebels in the former Yugoslav republic.

The arrivals in Kosovo on Monday came mostly from Skopje and its outskirts and said they had left because of growing tension between Macedonia's ethnic communities, Janowski said.

They also cited the threat of a military confrontation near Skopje.

Men without proper documentation were being turned back by Macedonian border guards, he added. Most of the new arrivals were women and children.

Many people had been driven by friends and relatives to within a few kilometres of the border and had walked the last few kilometres. Some people had crossed in their vehicles, the Geneva-based UNHCR said.

A few said they walked the 12-kilometre stretch from Skopje to the border.

On Monday, UN High Commissioner for Refugees Ruud Lubbers warned of a refugee crisis in a region already hosting more than one million displaced people from earlier conflicts.

"The fighting must stop now because tomorrow may already be too late," he said in a statement – GENEVA (AFP)